Device and method for manufacturing dental prosthesis

ABSTRACT

The invention relates to a device and a method for manufacturing a dental prosthesis with which and in which the data records for fabricated teeth are fitted into a virtual model of the oral situation. It is possible to subsequently directly manufacture the denture base or to insert the fabricated teeth in the model.

[0001] The invention relates to a device and a method for manufacturinga dental prosthesis.

[0002] A number of methods are known for the computer-assistedmanufacture of dental prostheses, such as milling of ceramic blanksaccording to 3-D data records (EP 904 743, DE 198 38 238 A1, DE 101 07451 A1, CEREC® system from Sirona, PROCERA® system from Degussa, LAVA®system from 3M-Espe), or the use of rapid prototyping methods (DE 101117 04 A1; DE 101 14 290 A1).

[0003] It is also known to perform the articulation function totally orpartially on the computer, rather than mechanically (“Verbatim,” Spring2000, U.S. Pat. No. 6,152,731 and U.S. Pat. No. 6,322,359).

[0004] The object of the invention is to develop a method formanufacturing dental prostheses whereby as much as possible of theentire planning and implementation proceeds in a computer-controlled orcomputer-assisted manner.

[0005] A manufacturing method for dental prostheses is described herein,in which the placement of the teeth is also virtually performed on thecomputer. The data records for fabricated teeth are fitted into avirtual model of the oral situation. The denture base can bemanufactured directly from the subsequentl data, using CAM methods, orthe fabricated teeth are inserted in the physical model.

[0006] The invention thus relates to a method for manufacturing a dentalprosthesis, having the following steps:

[0007] a Recording and digitizing (scanning) of the 3-dimensionalanatomical relationships in the oral cavity;

[0008] b Optional recording and digitizing (scanning) of the3-dimensional data on bite rims, including occlusion rims;

[0009] c Optional recording of mandibular data, which normally is takenon the patient for placement of the articulator;

[0010] d Processing of data record D0 from a and optionally b and/or cin such a way that the relevant anatomical structures for virtualplacement of teeth are securely affixed, and a virtual model is obtainedas data record D1;

[0011] e Selection of 3-D data records of fabricated, previously scannedteeth from a data record D3;

[0012] f Virtual placement of the teeth into the virtual model, datarecord D2; and

[0013] EITHER

[0014] j Transferring the virtual placement to the model by either apositioning template (for example, milled or rapid prototyped), ordirect placement of the fabricated teeth on the model;

[0015] k Affixing the teeth to the model;

[0016] l Attachment of the denture base;

[0017] OR

[0018] j Direct manufacture of the denture base, according to the datafor the virtual denture placement, with positioning aids for the finalcorrect positioning and affixing of the fabricated teeth.

[0019] The method proceeds as follows, by way of example: First, the3-dimensional anatomical relationships in the oral cavity are recordedin a data record, according to current, common methods. The data mayeither be recorded directly from the patient, such as with a 3-D camera,a microlaser optical device, a computerized tomography apparatus, or anultrasound apparatus, or the conventionally prepared plaster model isscanned. The data for optionally present bite rims and occlusion rimsmay likewise be recorded. It is also recommended that the mandibulardata, which normally are taken on the patient for placement of thearticulator, be recorded in the system. A data record D0 is thusproduced.

[0020] Next, the data are prepared in such a way that the geometricrelationships relevant for a virtual placement of teeth are present inthe computer as a 3-D model. This is referred to below as data recordD1.

[0021] At this point in the method, the dental prostheses to be usedlater must be selected by the user. This selection is made from a datarecord D3, which comprises previously scanned, synthetic prefabricateddental prostheses of various sizes and shapes. As a rule the desiredtooth shape (such as triangular or square) is selected. The geometricdata for the oral situation allow the system to determine the suitablesize of the teeth. The prefabricated dental prostheses have surfaceswhich allow an optimal occlusion. A suggestion from the system is thenobtained, so that the shape and size as well as the particular distancesbetween the teeth—or also a slightly offset configuration—result in anoptimal occlusion for a mandibular movement (data record D2). Inspectionof the aesthetic appearance can be performed directly on the screen. Itis also possible to generate a frontal view, and to insert this viewinto the digital photography of the patient's face.

[0022] At this point the user has the option to deviate from theoptimized model and produce a natural appearance by manually relocatingindividual teeth and observing the result directly on the screen. Forexample, using a drag and drop technique the position of an individualtooth can be moved in any desired spatial direction. The system correctsthe adjacent and opposing teeth immediately, so that an optimal bite isagain produced and a data record D2A is created. The occlusion data forall the opposing teeth may also be edited so that graphic or numericaldata are present which evaluate the modified situation as to whether itis more or less favorable than the previous situation. Of course, theprevious condition (D2) may be restored if the values are unsatisfactoryor incorrect, and then another dental position can be tried out—providedthat the aesthetic impression and the occlusion data are satisfactory.

[0023] Preferred embodiments of the invention are such that followingstep f

[0024] g Mandibular movements are simulated in/on the computer,

[0025] and, optionally following step g

[0026] h Inspection of the function and occlusion is performed in/on thecomputer,

[0027] and that following step h

[0028] i The placement of teeth is manually corrected, and a newcalculation is performed to adapt to the determined bite data andoptimal occlusion (data record D2A).

[0029] In each step of the method it is possible to reconstruct themandibular movements on the computer in the form of the known virtualarticulator.

[0030] After the operation on the virtual model is completed, thetransfer to the prosthesis can be performed; i.e., a denture base withpositioning aids for the teeth is manufactured according to the data forthe virtual placement of the teeth. Only the applicable selectedprefabricated teeth then need be inserted in the denture base.

[0031] The denture base can be directly produced, or a casting mold canbe made for the denture base. Methods such as milling or rapidprototyping may be used.

[0032] To ensure an exact fit of the synthetic teeth in the denturebase, the following methods, for example, can be used, which areexplained with reference to the figures.

[0033]FIG. 1A) on the left side shows the desired state, which isaffixed according to the virtual placement of the teeth; and on theright side shows the implementation according to the Lego blockprinciple 1 described below;

[0034]FIG. 1B) on the left side shows once again the desired state,which is affixed according to the virtual placement of the teeth; and onthe right side shows the implementation according to the attachmentprinciple 2 described below.

[0035] 1. Lego Block Principle (FIG. 1, A):

[0036] Specialized structures can be provided at the positions on thedenture base on which the synthetic teeth are to be placed. Thesestructures must:

[0037] a) Have a defined spatial orientation in six degrees of freedom,

[0038] b) Have geometric features which ensure congruence of shape withrespect to the particular base for the associated synthetic tooth,

[0039] c) Have a design which enables the tooth to be polymer-bonded,adhesive-bonded, or otherwise firmly attached.

[0040] As an example, it is possible to prepare a plateau on the denturebase which has three hemispherical prominences 1, configured in atriangle, which can be positioned unambiguously in recesses 2 in thedenture base congruent thereto. Five degrees of freedom are establishedby the spatial orientation of the position on the plateau. Theprominences are used to define the sixth degree of freedom (rotationabout the vertical axis of the tooth). The prominences can be designedso that the teeth may be snapped in, for example by a push-button shape.

[0041] 2. Attachment Principle (FIG. 1, B):

[0042] To avoid modifying the base of the synthetic teeth, a ring-likeshape 3 (in the figure, filled in with black in cross section) can becreated which exactly matches and defines the geometry of the respectivesynthetic tooth. The synthetic tooth can be inserted in this attachmentso that the spatial orientation of the tooth with reference to theattachment is always constantly defined. In the manufacture of thedenture base, corresponding shape-congruent recesses 4 are prepared oropened up which again ensure an exact, defined positioning of theattachment in all six degrees of freedom. Thus, the attachment can bepositioned in a defined manner and the corresponding synthetic tooth(including the known spatial orientation with respect to the attachment)can be affixed. After the synthetic tooth is affixed, the attachment canbe discarded.

[0043] The invention further relates to a device for carrying out themethod for manufacturing a dental prosthesis, essentially comprising thefollowing components:

[0044] a Scanning or recording apparatus for recording a digital 3-Ddata record D0 for the oral situation, on the patient or on a (plaster)model,

[0045] b Processing device for producing data for a virtual model of theoral situation (data record D1),

[0046] c 3-D data record for prefabricated dental prostheses D3,

[0047] d Processing module for fitting dental data D3 into the oralsituation data D1, with the creation of a virtual model D2 withintegrated dental prosthetic teeth (data record D2),

[0048] e Simulation module for the mandibular movements (virtualarticulator), in which modified positions of the teeth are tested andoptimized on virtual model D2,

[0049] f Device for manufacturing a positioning template or a denturebase from data records D2.

[0050] The individual components of the device are explained in detailbelow:

[0051] a The scanning or recording apparatus is, for example, a 3-Dcamera, a microlaser optical device, a computerized tomographyapparatus, or an ultrasound apparatus.

[0052] b The processing device for producing data for a virtual model ofthe oral situation (data record D1) is generally a computer, such as apersonal computer, in conjunction with an appropriate program(software).

[0053] c The 3-D data record for prefabricated dental prostheses D3 isdata originating from the scanning of dental prostheses.

[0054] d The processing module is generally a computer program createdfor this purpose.

[0055] e The virtual articulator is, for example, the system describedin “Verbatim,” Spring 2000.

[0056] f Devices for manufacturing a positioning template or a denturebase are known, for example rapid prototyping devices.

[0057] It should be understood that the preceding is merely a detaileddescription of one or more embodiment(s) of this invention and thatnumerous changes to the disclosed embodiment(s) can be made inaccordance with the disclosure herein without departing from the spiritor scope of the invention. The preceding description, therefore, is notmeant to limit the scope of the invention. Rather, the scope of theinvention is to be determined only by the appended claims and theirequivalents.

What is claimed is:
 1. Method for manufacturing a dental prosthesis,said method comprising the following steps: a Recording and digitizing(scanning) 3-dimensional, anatomical relationships in an oral cavity; bOptional recording and digitizing (scanning) 3-dimensional data on biterims; c Optional recording of mandibular data, which normally are takenon a patient for placement of an articulator; d Processing of datarecord D0 from a and optionally b and/or c in such a way that relevantanatomical structures for virtual placement of teeth are securelyaffixed, and a virtual model is obtained as data record D1; e Selectionof 3-D data records of fabricated, previously scanned teeth from a datarecord D3; f Virtual placement of the teeth into the virtual model, datarecord D2; and EITHER j Transferring the virtual placement to the modelby either a positioning template, or direct placement of the fabricatedteeth on the model; k Affixing the teeth to the model; l Attachment of adenture base; OR j Direct manufacture of the denture base, according tothe data for a virtual denture placement, with positioning aids for thefinal correct positioning and affixing of the fabricated teeth. 2.Method according to claim 1, wherein step a is performed by directlyrecording an oral situation using a 3-D camera.
 3. Method according toclaim 1, wherein step a is performed by scanning a plaster model. 4.Method according to claim 1, wherein following step f g Mandibularmovements are simulated in/on a computer.
 5. Method according to claim4, wherein following step g h The function and occlusion are inspectedin/on the computer.
 6. Method according to claim 5, wherein followingstep h i The placement of teeth is manually corrected, and a newcalculation is performed to adapt to the determined bite data andoptimal occlusion (data record D2A).
 7. Method according to claim 1,wherein in step j the positioning template is milled or rapidprototyped.
 8. Method according to claim 1, wherein in step b the biterims are occlusion rims.
 9. Device for the manufacture of a dentalprosthesis, essentially comprising the following: a Scanning orrecording apparatus for recording a digital 3-D data record D0 for anoral situation, on a patient or on a (plaster) model, b Processingdevice for producing data for a virtual model of the oral situation(data record D1), c 3-D data record for prefabricated dental prosthesesD3, d Processing module for fitting dental data D3 into the oralsituation data D1, with the creation of a virtual model D2 withintegrated dental prosthetic teeth (data record D2), e Simulation modulefor mandibular movements (virtual articulator), in which modifiedpositions of teeth are tested and optimized on virtual model D2, fDevice for manufacturing a positioning template or a denture base fromdata records D2.